Boe Hartman, who helped spearhead the creation of Goldman Sachs' consumer business, reflects on his most important lessons learned from the initiative.

In 2015, a tight-knit team of jeans-clad, tattooed software engineers worked feverishly inside Goldman Sachs, sequestered from the other technology teams. On November 17, they provisioned an account into the core billing system of Marcus by Goldman Sachs, the financial service firm's foray into consumer banking.

The code executed perfectly. The team, led by CTO Boe Hartman, who joined the company from Barclaycard only months earlier, celebrated with cake.

Less than a year later, on October 17, 2016, Marcus booked its first account. Since then, the business has originated more than $5 billion in consumer loans and more than $55 billion in deposits across the U.S. and U.K., according to a Marcus spokesman.

Here Hartman, who in August took on a leadership role in Goldman's digital strategy group, shares critical steps to inventing a new business within one of the world’s biggest banks. He also reflects on some of the most important lessons he learned, which are instructive for any technology leader driving a digital transformation.